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Boiling point

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Reference
Endpoint:
boiling point
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 103 (Boiling Point)
Version / remarks:
[adopted on 27 July 1995]
Deviations:
no
GLP compliance:
no
Type of method:
differential scanning calorimetry
Key result
Atm. press.:
1 010 hPa
Decomposition:
yes
Decomp. temp.:
232 °C

Capillary method

In the melt microscope beginning at a temperature of 165 °C the colour of the specimen starts to change from white to slightly yellowish brown, at 180 °C it appears reddish-brown. At 254 °C the specimen is of brown colour and starts to become liquid, at 255 °C a clear, brown liquid was obtained.

DSC/TGA

In the TGA test, a sample of the test item was heated from 30 °C to 675 °C in an inert gas atmosphere (N2). Starting at 30 °C a nearly constantly increasing weight loss was recorded. Until 240 °C (238.7 °C estimated onset) it lost 12.2 % of its weight. Above 238.7 °C (estimated onset) the weight loss increases significantly. At 670 °C a total loss of loss of approx. 72 % was recorded.

During the first heating period of the preliminary DSC test, an endothermic signal was recorded over a temperature range of approximately 30 °C … 170 °C. Thus, a second DSC test was focussed on the evaluation of this endothermic, however, as no re-crystallisation signal could be recorded in any cooling run (1st) and no phase transitions was observed in any successive heating or procedure this endothermic is possibly attributed to a solid-solid phase transformation, but not to a melting behaviour of the main component. This corresponds to the visual observation where the substance remained solid until 254 °C.

At the 2nd heating run of the preliminary DSC test the sample was heated up to 255 °C. The recorded discontinuities above 231.8 °C (estimated onset) indicate a beginning decomposition of the test item, which corresponds to the increasing weight loss and the visual observation in the melt microscope (colour change).

In order to provide evidence for this assumption, a degradation test was performed during which 21.6204 mg of the sample were heated to 255°C for 5 minutes (visually observed melting point) and the remaining residue war characterised by NMR spectroscopy. A weight loss of 31.7 % was recorded and according to the NMR analysis, the residue provided a huge amount of underivatised sulfonatosuccinic acid, which indicates a degradation of the ester bond.

No thermodynamic melting point could be identified up to beginning degradation at 232 °C (1010 hPa).

Conclusions:
boiling point > 232 °C (decomposition at 232°C)
Executive summary:

The boiling temperature of the freeze-dried test material was determined with the DSC method according to OECD 103 and EU method A.2 in a non-GLP study to be >232°C. At 232°C, decomposition was observed.

This information on the boiling temperature is considered to be relevant and reliable for the further risk assessment.

Description of key information

boiling point > 232°C (decomposition at 232°C)

Key value for chemical safety assessment

Additional information

The boiling temperature of the freeze-dried test material was determined with the DSC method according to OECD 103 and EU method A.2 in a non-GLP study to be >232°C. At 232°C, decomposition was observed.

This information on the boiling temperature is considered to be relevant and reliable for the further risk assessment.